// Copyright 2017 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

// Package consensus implements different Ethereum consensus engines.
package consensus

import (
	"math/big"

	"github.com/truechain/truechain-engineering-code/common"
	"github.com/truechain/truechain-engineering-code/core/state"
	"github.com/truechain/truechain-engineering-code/core/types"
	"github.com/truechain/truechain-engineering-code/params"
	"github.com/truechain/truechain-engineering-code/rpc"
)

// ChainReader defines a small collection of methods needed to access the local
// blockchain during header and/or uncle verification.
type ChainReader interface {
	// Config retrieves the blockchain's chain configuration.
	Config() *params.ChainConfig

	// CurrentHeader retrieves the current header from the local chain.
	CurrentHeader() *types.Header

	// GetHeader retrieves a block header from the database by hash and number.
	GetHeader(hash common.Hash, number uint64) *types.Header

	// GetHeaderByNumber retrieves a block header from the database by number.
	GetHeaderByNumber(number uint64) *types.Header

	// GetHeaderByHash retrieves a block header from the database by its hash.
	GetHeaderByHash(hash common.Hash) *types.Header

	// GetBlock retrieves a block from the database by hash and number.
	GetBlock(hash common.Hash, number uint64) *types.Block
}

// ChainSnailReader defines a small collection of methods needed to access the local
// block chain during header and/or uncle verification.
// Temporary interface for snail
type SnailChainReader interface {
	// Config retrieves the blockchain's chain configuration.
	Config() *params.ChainConfig

	// CurrentHeader retrieves the current header from the local chain.
	CurrentHeader() *types.SnailHeader

	// GetHeader retrieves a block header from the database by hash and number.
	GetHeader(hash common.Hash, number uint64) *types.SnailHeader

	// GetHeaderByNumber retrieves a block header from the database by number.
	GetHeaderByNumber(number uint64) *types.SnailHeader

	// GetHeaderByHash retrieves a block header from the database by its hash.
	GetHeaderByHash(hash common.Hash) *types.SnailHeader

	// GetBlock retrieves a block from the database by hash and number.
	GetBlock(hash common.Hash, number uint64) *types.SnailBlock
}

// ChainFastReader defines a small collection of methods needed to access the local
// fast blockChain during header and/or uncle verification.
type ChainFastReader interface {
	// Config retrieves the fast blockChain's chain configuration.
	Config() *params.ChainConfig

	// CurrentHeader retrieves the current fast header from the local chain.
	CurrentHeader() *types.FastHeader

	// GetHeader retrieves a fast block header from the database by hash and number.
	GetHeader(hash common.Hash, number uint64) *types.FastHeader

	// GetHeaderByNumber retrieves a fast block header from the database by number.
	GetHeaderByNumber(number uint64) *types.FastHeader

	// GetHeaderByHash retrieves a fast block header from the database by its hash.
	GetHeaderByHash(hash common.Hash) *types.FastHeader

	// GetBlock retrieves a fast block from the database by hash and number.
	GetBlock(hash common.Hash, number uint64) *types.FastBlock
}

// Engine is an algorithm agnostic consensus engine.
type Engine interface {
	// Author retrieves the Ethereum address of the account that minted the given
	// block, which may be different from the header's coinbase if a consensus
	// engine is based on signatures.
	Author(header *types.Header) (common.Address, error)
	AuthorSnail(header *types.SnailHeader) (common.Address, error)

	// VerifyHeader checks whether a header conforms to the consensus rules of a
	// given engine. Verifying the seal may be done optionally here, or explicitly
	// via the VerifySeal method.
	VerifyHeader(chain ChainReader, header *types.Header, seal bool) error
	VerifySnailHeader(chain SnailChainReader, header *types.SnailHeader, seal bool) error

	// VerifyFastHeader checks whether a fast chain header conforms to the consensus rules of a
	// given engine. Verifying the seal may be done optionally here, or explicitly
	VerifyFastHeader(chain ChainFastReader, header *types.FastHeader, seal bool) error

	// VerifyHeaders is similar to VerifyHeader, but verifies a batch of headers
	// concurrently. The method returns a quit channel to abort the operations and
	// a results channel to retrieve the async verifications (the order is that of
	// the input slice).
	VerifyHeaders(chain ChainReader, headers []*types.Header, seals []bool) (chan<- struct{}, <-chan error)
	VerifySnailHeaders(chain SnailChainReader, headers []*types.SnailHeader, seals []bool) (chan<- struct{}, <-chan error)

	// VerifyFastHeaders is similar to VerifyFastHeader, but verifies a batch of fast headers
	// concurrently. The method returns a quit channel to abort the operations and
	// a results channel to retrieve the async verifications (the order is that of
	// the input slice).
	VerifyFastHeaders(chain ChainFastReader, headers []*types.FastHeader, seals []bool) (chan<- struct{}, <-chan error)

	// VerifyUncles verifies that the given block's uncles conform to the consensus
	// rules of a given engine.
	VerifyUncles(chain ChainReader, block *types.Block) error
	VerifySnailUncles(chain SnailChainReader, block *types.SnailBlock) error

	// VerifySeal checks whether the crypto seal on a header is valid according to
	// the consensus rules of the given engine.
	VerifySeal(chain ChainReader, header *types.Header) error
	VerifySnailSeal(chain SnailChainReader, header *types.SnailHeader) error

	// Prepare initializes the consensus fields of a block header according to the
	// rules of a particular engine. The changes are executed inline.
	Prepare(chain ChainReader, header *types.Header) error
	PrepareSnail(chain SnailChainReader, header *types.SnailHeader) error

	// PrepareFast initializes the consensus fields of a fast chain block header according to the
	// rules of a particular engine. The changes are executed inline.
	PrepareFast(chain ChainFastReader, header *types.FastHeader) error

	// Finalize runs any post-transaction state modifications (e.g. block rewards)
	// and assembles the final block.
	// Note: The block header and state database might be updated to reflect any
	// consensus rules that happen at finalization (e.g. block rewards).
	Finalize(chain ChainReader, header *types.Header, state *state.StateDB, txs []*types.Transaction,
		uncles []*types.Header, receipts []*types.Receipt, fruits []*types.Block) (*types.Block, error)
	FinalizeSnail(chain SnailChainReader, header *types.SnailHeader, state *state.StateDB,
		uncles []*types.SnailHeader, fruits []*types.SnailBlock, signs []*types.PbftSign) (*types.SnailBlock, error)

	// FinalizeFast runs any post-transaction state modifications (e.g. block rewards)
	// and assembles the final block.
	// Note: The block header and state database might be updated to reflect any
	// consensus rules that happen at finalization (e.g. block rewards).
	FinalizeFast(chain ChainFastReader, header *types.FastHeader, state *state.StateDB,
		txs []*types.Transaction, receipts []*types.Receipt) (*types.FastBlock, error)

	//Call allocation gas before FinalizeFast
	FinalizeFastGas(state *state.StateDB, fastNumber *big.Int, fastHash common.Hash, gasLimit *big.Int) error

	// Seal generates a new block for the given input block with the local miner's
	// seal place on top.
	Seal(chain ChainReader, block *types.Block, stop <-chan struct{}) (*types.Block, error)
	SealSnail(chain SnailChainReader, block *types.SnailBlock, stop <-chan struct{}) (*types.SnailBlock, error)

	// ConSeal generates a new block for the given input block with the local miner's
	// seal place on top.
	ConSeal(chain ChainReader, block *types.Block, stop <-chan struct{}, send chan *types.Block)
	ConSnailSeal(chain SnailChainReader, block *types.SnailBlock, stop <-chan struct{}, send chan *types.SnailBlock)

	// CalcDifficulty is the difficulty adjustment algorithm. It returns the difficulty
	// that a new block should have.
	CalcDifficulty(chain ChainReader, time uint64, parent *types.Header) *big.Int
	CalcSnailDifficulty(chain SnailChainReader, time uint64, parent *types.SnailHeader) *big.Int

	// APIs returns the RPC APIs this consensus engine provides.
	APIs(chain ChainReader) []rpc.API
}

//Election module implementation committee interface
type CommitteeElection interface {
	//Verify the fast chain committee signatures in batches
	VerifyFastBlockSigns(pvs []*types.PbftSign) (cfvf []types.CommitteeMember)

	//Get a list of committee members
	GetCommittee(FastNumber *big.Int, FastHash common.Hash) (*big.Int, []*types.CommitteeMember)
}

// PoW is a consensus engine based on proof-of-work.
type PoW interface {
	Engine

	// Hashrate returns the current mining hashrate of a PoW consensus engine.
	Hashrate() float64
}
